1. Field of the Invention
This invention relates to the manufacture of flat glass by a method in which glass in ribbon form is produced on a molten metal support.
2. Description of the Prior Art
Flat glass in ribbon form has been produced on a bath of molten metal by the float process in which a buoyant body of molten glass is formed on a molten metal bath and that body is advanced in ribbon form along the bath. The temperature regime to which the advancing glass is subjected can be controlled in relation to tractive forces applied to the ultimate ribbon of glass at the outlet end of the bath and, by means of top rolls, to the margins of the glass as the ribbon is being formed. Regulation of these factors determines the thickness of the ribbon of glass produced. Only the margins of the upper surface of the ribbon of glass have been contacted while the glass is in a deformable state, although for surface modification of the glass its upper surface has been contacted by a body of molten material which does not impair the fire finished surface of the glass.
In some ways of operating when the glass has been thinned by traction operating from the outlet end of the bath, the margins of the buoyant body of molten glass which is formed at the hot end of the bath, have been caused to wet on to refractory members at the sides of the tank structure so as to provide a marginal reaction to the traction forces.
The present invention is based on a new concept of manufacturing thin flat glass on a molten metal support by providing a reaction to traction right across the width of the molten glass from which an ultimate glass ribbon is being drawn.
This new concept can be used for the manufacture of a wide range of thicknesses of flat glass from 10 mm thick down to glass foil 0.005 mm thick. More especially the present invention is adapted to the production of very thin flat glass and glass foil.